I reckon I'm pretty useful with a hand file, which is great for a quick 'polish' on an otherwise reasonably OK chain, but there are occasions when I've 'been gardening' and gone into roots or nipped the ground or a stone or bit of wire and the chain is well blunt. I found last week one side of the chain was far more blunt and despite attempted hand filing the saw kept curving sideways through thick wood. Under those circumstances its difficult to get back to any sort of decent edge, a more drastic 'restoration' is called for to prolong the life of the chain and I've been researching mechanical options.
Rob at chainsawbars.co.uk (he of the Alaskan mill) reckons the quickest best way to sharpen back to a factory edge, particularly when working with long bars is to go for a 12v portable sharpener. Cheapest would be something like a basic Oregon or Granberg at around the £30 mark.
https://www.youtube.com/watch?v=K11rAKksX98
For a more precise rather than hand-held version, there's the Granberg (also known as Sawtune) precision grinder (£60ish), which clamps on to the chain bar. On Arbtalk pro users seem to unanimously say its a great bit of kit which will get the chain cutting like new again. When you've a heck of a lot of old hard oak to go through as I have, you need the best edge possible or else its exhausting. At the end of the next video you can see how an old chain sharpened by Rob with very little tooth left on it is taken back to a really 'new' edge and then goes through thick hardwood like proverbial butter. The grinding stones cost about £2.50 each in packs of three, and each will sharpen a chain about three times, so its about 80p a shout to resurrect an otherwise useless chain. A handfile would do for quick job in between 12V grinder treatments.
https://www.youtube.com/watch?v=LEdu4u6dnGA&list=UU9K0KfLNH84tuWi2VjlSlCg
Wonder if anyone else has comments or experience of 12V grinders before I probably take the plunge.